Phase stable multiple emulsion compositions

ABSTRACT

W 1 -O-W 2  emulsions are disclosed in which the W 1 /O emulsion comprises an internal aqueous phase containing optional benefit agent and an oil phase surrounding it, and, around this is found an external isotropic aqueous phase comprising surfactant system and specific thickeners. Selection of surfactant system and thickener is critical to the multiple emulsion composition not phase separating.

FIELD OF THE INVENTION

The present invention relates to liquid surfactant composition, e.g., liquid shower gels or liquid shampoos, comprising multiple emulsions. In particular, this invention relates to such compositions which may comprise high levels of surfactants: microscopically these compositions maintain multiple emulsion droplet integrity while macroscopically there is little or no phase separation.

BACKGROUND OF THE INVENTION

Multiple emulsion systems (broadly defined as systems in which water/oil and oil/water emulsion co-exist) are very valuable because these permit incorporation and enhanced delivery of benefit agents. Thus, these multiple emulsions have been used for many years, for example, in cosmetic and pharmaceutical areas to deliver cosmetic or pharmacological benefit agents (see for Example, U.S. Pat. No. 5,306,498 to Vesperini; or U.S. Pat. No. 5,567,426 to Nadaud et al.). The level of high HLB (>10) cleansing surfactant in almost all the cosmetic and pharmaceutical art referred to above is below 5% by wt. of the compositions. If the high HLB surfactant concentration in the above referred to art were significantly increased, the multiple emulsion droplets would become less and less stable, leading to phase separation. In U.S. Pat. Nos. 5,656,280 and 5,589,177 to Herb et al, the multiple emulsion droplets are stabilized in high levels of conditioning surfactants which form lamellar liquid crystals.

In applicants' copending application entitled “Stable Multiple Emulsion Composition” and filed on same date as the subject application, applicants found multiple emulsion systems which employed surfactant systems which were in an isotropic phase which at the same time did not rapidly destabilize the multiple emulsion droplets. It is particularly advantageous to use surfactant systems which are isotropic because these systems provide improved foam/lather and because they can be formed using a much wider range of surfactant.

While the final compositions of that invention are microscopically stable in that the multiple emulsion droplets maintain their integrity, they phase separate over time. In the subject invention, the compositions do not phase separate due to specific selection of an external surfactant system in combination with a stabilizing natural gum polymer which forms a gelled external aqueous phase with a relatively high concentration of surfactant. Compositions which employ similar technology (i.e. gelled external aqueous phase) are described in U.S. Pat. No. 5,306,498 to Vesperini, U.S. Pat. No. 4,083,798 to Versteeg, U.S. Pat. No. 5,332,595 to Gaonkar, U.S. Pat. Nos. 5,576,064 and 5,656,263 both to Fructus, and U.S. Pat. No. 5,567,426 to Nadaud. In all of these aforementioned compositions, however, the level of high HLB external surfactant was in one case only 5% and in most cases zero.

It is the object of this invention to provide a gelled isotropic external surfactant phase which contains high levels of surfactant where the integrity of the multiple emulsion droplet is maintained and the composition does not phase separate.

BRIEF SUMMARY OF THE INVENTION

Unexpectedly, applicants have now found that through specific selection of an external surfactant system in combination with a stabilizing natural gum polymer which forms a gelled external aqueous phase with a relatively high concentration of surfactant, a multiple emulsion system is formed which allows delivery of desirable benefit agent(s) while simultaneously maintaining both the integrity of the multiple emulsion droplets and physical stability of the composition (i.e. the bottom clear layer formed due to phase separation should be less than 20 volume percent of the total volume of the sample for a period of at least 45 days at room temperature.)

Specifically, the invention relates to the selection of natural gum polymers and surfactant(s) or combinations of surfactants which form a gelled external phase for the multiple emulsions described above.

More specifically, the invention comprises a water-in-oil-in-water (W₁-O-W₂) multiple emulsion wherein the water-in-oil (W₁/O) emulsion itself comprises an internal aqueous phase (W₁) which contains a solute and optional surfactant; an oil phase O (an oil combined with a low HLB emulsifier, e.g., emulsifier with HLB less than 10) surrounding the internal aqueous phase; and a topically active compound which may be in either the aqueous W₁ or in O. The W₁O phase is surrounded by an external aqueous isotropic phase (W₂) containing a high level of cleansing surfactant, optional topically active compound (which may be same or different as first optional topically active compound), optional solute (It should be understood that some solute will almost always be present in the surfactant or will be formed when adjusting pH) and a stabilizing natural gum polymer. It is a criticality of the invention that the natural gum stabilizer and the selected surfactant(s) form a gel. As in the copending application, another criticality is that the surfactant phase W₂ must not contain an anionic surfactant with an amido group. Furthermore, the W₂ surfactant phase must be isotropic. The isotropic phase in turn is formed by selection of a specific surfactant system which must not contain an anionic surfactant with an amido group.

The oil in the O phase (e.g., light mineral oil, hexadecane, octyl palmitate) should preferably not comprise (1) more than 50% unsaturated compounds; or (2) should not be a volatile silicone (e.g., a silicone having viscosity of 10 centistokes or less).

As noted above, the invention can be distinguished from prior art U.S. Pat. No. No. 5,306,498 (Vesperini) U.S. Pat. No. 4,083,798 (Versteeg) U.S. Pat. No. 5,332,595 (Gaonkar), 5,576,064 and U.S. Pat. No. 5,656,263 (Fructus), and U.S. Pat. No. 5,567,426 (Nadaud) because our invention uses surfactant levels of 10.5% or greater whereas the aforementioned compositions use levels of only 0-5% external surfactant.

In particular, the invention comprises a W₁-O-W₂ multiple emulsion composition comprising:

(1) about 1% to 99% by wt. of the composition, preferably 2% to 90% by wt., more preferably 5% to 80%, more preferably 5 to 50% of a W₁/O emulsion comprising;

(a) about 1% to 99% of said emulsion of an internal aqueous phase comprising (i) water; (ii) 0.01 to 30% solute; and (iii) 0 to 30% surfactant;

(b) about 0.5% to about 99%, preferably 1 to 80% of the emulsion of an oil phase surrounding said internal aqueous phase comprising a non-volatile silicone compound, a volatile hydrocarbon compound, a non-volatile hydrocarbon compound or a mixture thereof;

(c) about 0.1 to 20%, preferably 1 to 15%, more preferably 1.5 to 15% of a low HLB emulsifier (e.g., having HLB under 10); and

(d) a topically effective amount (e.g., 0.01 to 40%, preferably 0.05 to 15% by wt.) of a first topically active compound which may be found in either aqueous phase (a) and/or oil phase (b); and

(2) about 1 to 99% by wt., preferably 20 to 95% by wt. of an external isotropic aqueous phase W₂ comprising non-amido anionic and/or other surfactants. The composition contains all non-amido anionic or all amphoteric surfactant, or combinations of the two. The surfactant typically will comprise 2-80% of the aqueous phase and 0.01 to 10% stabilizing natural gum polymer. The composition optionally contains a second topically effective compound, typically 0-40% by wt. of the external phase to perform a function identical to, similar to or different from the first topically active compound and solute. It is preferred that in systems where the external surfactant W2 is comprised entirely of or contains a majority of anionic surfactant, that a nonionic gum polymer is used. Conversely, in systems where the external surfactant W2 is comprised entirely of or contains a majority of amphoteric surfactant, it is preferred that an anionic gum polymer is used.

The W₁-O-W₂ multiple emulsion compositions are physically stable (e.g., typically they will not phase separate at room temperature for at least 45 days and exhibit exceptional esthetic and functional properties. The W₁-O-W₂ multiple emulsion compositions are liquids or creams, and are capable of effectively delivering one or more topically active compounds to the skin or hair from a single composition.

BRIEF DESCRIPTION OF FIGURES

Each figure is a plot of viscosity vs Haake RV06 spindle speed.

In FIG. 1, it is clear that the addition of 3% by weight of an anionic natural gum (example carrageenan) to an amphoteric surfactant (example cocamidopropyl betaine) yields a gelled external W2 phase i.e. a viscoelastic solution that exhibits shear thinning behavior.

In FIG. 2, it is clear that the addition of 1% by weight of a nonionic natural gum (example locust bean) to an anionic surfactant (example sodium laureth sulfate) yields a gelled external W2 phase. In each of these cases, addition of the gum to the surfactant has transformed the rheology of the W2 phase from a Newtonian low viscosity to a shear thinning, high viscosity gel. This gelled external (W2) phase, resulting from proper surfactant and stabilizer selection, helps keep the multiple emulsion from phase separating while still rendering the composition pourable. A viscosity of at least 6000 cps at a spindle speed of 5 rpm and a viscosity of no more than 9000 cps at 50 rpm are preferred to render the composition phase stable as well as pourable.

DETAILED DESCRIPTION OF THE INVENTION

The present invention relates to W₁-O-W₂ multiple emulsions where the integrity of the multiple emulsion droplet is maintained and the composition does not phase separate. These formulations comprise:

(1) 1 to 99% W₁/O emulsion comprising about 1% to 99% of W₁ (containing water, solute and optional surfactant), and 0.5 to 99% of O phase (containing oil compound and low HLB emulsifier). A topically active agent may be present in W₁ phase, O phase or both; and

(2) about 1% to 99% by wt. of an external aqueous phase comprising non-amido anionic and/or amphoteric surfactant, a stabilizing natural gum polymer, an optional second topically effective compound, and solute.

The external aqueous phase W2 contains a high concentration (i.e., 15% by wt. or greater, preferably 16% or greater, preferably 17 to 75%, more preferably 20 to 70%, more preferably 22% to 60%, more preferably 25 to 50% by wt. of the composition) of surfactant which is isotropic. It is a criticality of the invention that the natural gum stabilizer and the selected surfactant(s) form a gel. Applicants have found unexpectedly that in systems where the external surfactant W2 is comprised entirely of or contains a majority of anionic surfactant, that a nonionic gum polymer should be used. Conversely, in systems where the external surfactant W2 is comprised entirely of or contains a majority of amphoteric surfactant, that an anionic gum polymer should be used. This differs from prior art in that the external phase now contains high levels of cleansing surfactant and the choice of stabilizing polymer is subject to the above criticalities.

The invention will now be described in greater detail.

The Water-in-Oil (W₁/O) Emulsion

The W₁/O emulsion comprises an internal aqueous phase W₁ with water, solute and optional surfactant, and an oil phase O.

Generally the water, solute and first topically-active compound comprise the internal aqueous phase of the W₁/O emulsion (active compound may also be in oil phase if oil compatible). That is, the W₁ phase comprises droplets containing water, solute and possibly a first topically-active compound. For example, droplets containing water, solute and a first topically-active compound (W₁) may have a diameter ranging from about 0.01 to about 75 μm and may be enveloped by a membrane or film comprising the oil phase. The contents of the internal aqueous phase (W₁) therefore do not contact the external aqueous phase (W₂) of the W₁-O-W₂ multiple emulsion.

The primary W₁/O emulsion is present in a W₁-O-W₂ multiple emulsion composition in an amount of about 1% to about 99%, preferably 2% to 90%, more preferably about 5% to about 80%, by weight of the multiple emulsion composition. To achieve the full advantage of the present invention, the primary W₁/O emulsion is present in an amount of about 10% to about 80% by weight of the multiple emulsion composition.

The Internal Aqueous Phase

The (W1) internal aqueous phase constitutes about 1% to about 99% by weight of the emulsion, an oil phase separates the internal aqueous phase (W₁) of the emulsion from the external aqueous phase (W₂).

The internal aqueous phase (W₁) of the present W₁-O-W₂ multiple emulsion compositions generally comprise water, solute and an optional first topically-active compound (which may also be found in oil phase alone or in both). The internal aqueous phase can further comprise additional topically-active compounds and/or optional water soluble compounds capable of providing a desired esthetic or functional effect, such as a fragrance.

The aqueous phase (W₁) comprises about 1% to about 99%, and preferably about 10% to about 95%, by weight of the W₁/O emulsion. To achieve the full advantage of the present invention, the aqueous phase comprises about 25% to about 95% by weight of the W₁/O emulsion.

Topically-Active Compounds

In accordance with an important feature of the present invention, a wide variety of topically active compounds can be incorporated into the W₁/O emulsion as the first topically active compound. If found in the W₁ phase, the topically active compounds are water soluble or water dispersible and include both cosmetic and other compounds that act upon contact with the skin or hair. The first topically active compound is present in a sufficient amount to perform its intended function, typically in an amount of about 0.01% to about 40% by weight, preferably 0.05 to 15% of the W₁O emulsion.

The first topically active compound typically remains on the skin or hair after application, as opposed to being rinsed from the skin or hair. However, particular first topically active compounds are designed to be rinsed from the skin or hair after the compound performs its intended function.

In accordance with an important feature of the present invention, the first topically active compound can be incorporated into the aqueous phase or into the oil phase of the primary emulsion. Whether a particular first topically active compound is incorporated into the aqueous phase or the oil phase of the primary emulsion is related to the solubility of the topically active composition in water. In preferred embodiments, the first topically active compound is water soluble and is incorporated into the internal W₁ aqueous phase. However, a more hydrophobic agent may be used in the oil phase.

As used herein, the term “water soluble” means water soluble or water dispersible. A water soluble compound has a water solubility of at least 0.1 g (grams) per 100 ml (milliliters) of water and forms a true solution. A water soluble compound can be inherently water soluble or can be made water soluble by the addition of a solubilizing compound, such as a coupling agent, a co-surfactant, or a solvent. A water dispersible compound remains dispersed in water for at least the time period necessary to manufacture the primary W₁/O emulsion, i.e., at least about one hour.

In addition, the topically active compound can be incorporated into the external aqueous phase W₂ to achieve enhanced efficacy.

The topically active compound therefore can be one of, or a combination of, a cosmetic compound, a medicinally active compound or any other compound that is useful upon topical application to the skin or hair. Such topically active compounds include, but are not limited to, hair and skin conditioners, hair and skin cleansers, hair fixatives, hair dyes, hair growth promoters, deodorants, skin care compounds, permanent wave compounds, hair relaxers, hair straighteners, antibacterial compounds, antifungal compounds, anti-inflammatory compounds, topical anesthetics, sunscreens and other cosmetic and medicinal topically effective compounds.

In accordance with one aspect of the present invention, the topically active compound comprises a water soluble hair conditioner, such as a quaternary ammonium compound. Quaternary ammonium compounds are substantive to the hair and are excellent hair conditioners, but have a well known incompatibility with anionic surfactants and anionic dyes. Therefore, quaternary ammonium compounds generally are not a component in shampoo conditioner compositions or anionic dye-based compositions, but are applied to the hair from a separate conditioning composition.

The water soluble quaternary ammonium compounds have the general structural formula:

wherein R₁ is an alkyl group including from about 8 to about 18 carbon atoms; R₂ is selected from the group consisting of an alkyl group including from about 8 to about 18 carbon atoms, a hydrogen atom, a methyl group, an ethyl group, a hydroxymethyl group and a hydroxyethyl group; R₃ is selected from the group consisting of a benzyl group, a hydrogen atom, a methyl group, a methyl group, a hydroxymethyl group and a hydroxyethyl group; R₄ is selected from the group consisting of a hydrogen atom, a methyl group, an ethyl group, a hydroxymethyl group and a hydroxyethyl group; and X is an anion. The quaternary nitrogen of the water soluble quaternary ammonium compound also can be a component of a heterocyclic nitrogen containing moiety, such as morpholine or pyridine. The anion of the quaternary ammonium compound can be any common anion, such as chloride, methosulfate, ethosulfate, nitrate, bromide tosylate, acetate, or phosphate.

The water soluble quaternary ammonium compounds have one or two long chain alkyl groups containing from about 8 to about 18 carbon atoms. The long chain alkyl groups also can include, in addition to, or in replacement of, carbon and hydrogen atoms, either linkages or similar water solubilizing linkages. The remaining two or three substituents of the quaternary nitrogen of the quaternary ammonium compound can be hydrogen; or benzyl, or short chain alkyl or hydroxyalkyl groups, such as methyl, ethyl, hydroxymethyl or hydroxyethyl groups; or combinations thereof, either of the same or different identity.

Exemplary water soluble quaternary ammonium compounds include, but are not limited to lautrimonium chloride; Quaternium-16; lauralkonium chloride; olealkonium chloride; dilauryldimonium chloride; cetalkonium chloride; dicetyldimonium chloride; laurylpyridinium chloride; cetylpyridinium chloride; soyatrimonium chloride; Polyquaternium-6; Polyquaternium-7; guarhydroxypropyltrimonium chloride; Polyquaternium-11; Polyquaternium-5; Polyquaternium-10; Polyquaternium-24; cetrimonium chloride; Quaternium-24; mytrimonium chloride; PEG-2 cocomonium chloride; PEG-2 cocoyl quaternium-4; PEG-15 cocoyl quaternium-4; PEG-2 stearyl quaternium-4; PEG-2 oleyl quaternium-4; and PEG 15 olelyl quaternium-4, and mixtures thereof, wherein the compound designation is provided by the Cosmetic, Toiletry and Fragrance Association, Inc. in the CTFA Cosmetic Ingredient Dictionary, 4th Ed., 1991, hereinafter referred to as the CTFA Dictionary. Other water soluble quaternary ammonium compounds are listed in the CTFA Cosmetic Ingredient Handbook, 1st Ed., 1988 (hereinafter the CTFA Handbook) at pages 40-42, incorporated herein by reference.

Other water soluble hair conditioners also can be used as the first topically active compound. Such hair conditioners include, but are not limited to, fatty amine salts, ethoxylated fatty amine salts, dimethicone copolyols, protonated polyethylenimines, protonated ethoxylated polyethylenimines, soluble animal collagen, lauramine oxide, cationic polymers, numerous other water soluble hair conditioners listed in the CTFA Handbook at page 71-73, incorporated herein by reference, and mixtures thereof.

In addition to hair conditioners, a skin conditioner can be used as the first topically active compound. Skin conditioning agents include, but are not limited to, humectants, such as fructose, glucose, glycerin, propylene glycol, glycereth-26, mannitol and urea; pyrrolidone carboxylic acid; hydrolyzed lecithin; coco-betaine; cysteing hydrochloride; glutamine; PPG-15; sodium gluconate; potassium aspartate; olelyl betaine, thiamine hydroxychloride; sodium laureth sulfate; sodium hyaluronate; hydrolyzed proteins; hydrolyzed keratin; amino acids; amine oxides; water soluble derivatives of vitamins A, E and D; amino functional silicones; ethoxylated glycerin; alpha-hydroxy acids and salts thereof; water soluble fatty oil derivatives, such as PEG-24 hydrogenated lanolin, almond oil, grape seed oil and caster oil; numerous other water soluble skin conditioners listed in the CTFA Handbook, pages 79-84, incorporated herein by reference; and mixtures thereof. Other conditioners include alpha hydroxy acids such as lactic acid, glycolic acid or their salts thereof.

The first topically active compound also can be a hair fixative or film former that imparts style retention properties to hair, i.e., sets the hair. The hair fixative typically is a homopolymer, a copolymer, or a terpolymer. The polymers can be nonionic, amphoteric, anionic or cationic. Examples of hair fixatives include, but are not limited to, an acrylamide copolymer; an acrylamide/sodium acrylate copolymer; a polystyrene sulfonate; a polyethylene oxide; a water dispersible polyester; a cationic cellulose; an acrylate/ammoniummethacrylate copolymer; an aminoethylacrylate phosphate/acrylate copolymer; a polyacrylamide; Polyquaternium-1; Polyquaternium-2; Polyquaternium-4; Polyquaternium-4; Polyquaternium-5; Polyquaternium-7; Polyquaternium-8; Polyquaternium-9; Polyquaternium-10; Polyquaternium-11; Polyquaternium-12; Polyquaternium-13; Polyquaternium-14; Polyquaternium-15; Polyquaternium-16; Polyquaternium-28; a PVP (polyvinylpyrrolidone); a PVP/dimethylaminoethylmethacrylate copolymer; a PVP/ethyl methacrylate/methacrylic acid copolymer; a carboxylated polyvinyl acetate; vinyl/caprolactam/PVP/dimethylaminoethyl methacrylate copolymer (GAFFIX VC713); a PVP/vinyl acetate copolymer; a sodium acrylate/vinyl alcohol copolymer; sodium carrageenan; a vinyl acetate/crotonic acid copolymer; numerous other water soluble hair fixatives listed in the CTFA Handbook at pages 73-74, incorporated herein by reference; and mixtures thereof. Numerous hair fixatives also are disclosed in U.S. Pat. No. 5,277,899, incorporated herein by reference.

In addition, the first topically active compound can be a water soluble hair dye, such as, but not limited to, m-aminophenol hydrochloride, p-aminophenol sulfate, 2,3-diaminophenol hydrochloride, 1,5-naphthalenediol, phenylenediamine hydrochloride, sodium picramate, water soluble cationic dyes, water soluble anionic dyes, water soluble FD&C dyes, like Blue No. 1, Blue No. 2, Red No. 3, Red No. 4, or Red No. 40, water soluble D&C dyes, like Yellow No. 10, Red No. 22 or Red No. 28, and pyrogallol. Numerous other hair dyes are listed in the CTFA Handbook, pages 70-71, incorporated herein by reference.

The first topically active compound also can be an antioxidant, like ascorbic acid or erythorbic acid; or a fluorescent whitening agent or optical brightener, like a distyrylbiphenyl derivative, stilbene or a stilbene derivative, a pyralozine derivative or a coumarin derivative. In addition, a self-tanning compound, like dihydroxy acetone, or a hair growth promoter, or a hair bleaching agent, like a perborate or a persulfate salt, can be the first topically active compound.

The first topically active compound also can be a deodorant compound, such as an astringent salt or a bioactive compound. The astringent salts include organic and inorganic salts of aluminum, zirconium, zinc, and mixtures thereof. The anion of the astringent salt can be, for example, sulfate, chloride, chlorohydroxide, alum, formate, lactate, benzyl sulfonate orphenyl sulfonate. Exemplary classes of antiperspirant astringent salts include aluminum halides, aluminum hydroxyhalides, zirconyl oxyhalides, zirconyl hydroxyhalides, and mixtures thereof.

Exemplary aluminum salts include aluminum chloride and the aluminum hydroxyhalides having the general formula Al₂(OH)_(x)Q_(y)XH₂O, wherein Q is chlorine, bromine or iodine; x is about 2 to about 5; x+y is about 6, wherein x and y are not necessarily integers; and X is about 1 to about 6. Exemplary zirconium compounds include zirconium oxy salts and zirconium hydroxy salts, also referred to as zirconyl salts and zirconyl hydroxy salts, and represented by the general empirical formula ZrO(OH)_(2−nz)I_(z), wherein z varies from about 0.9 to about 2 and is not necessarily an integer; n is the valence of L; 2−nz is greater than or equal to 0; and L is selected from the group consisting of halides, nitrate, sulfamate, sulfate, and mixtures thereof.

Exemplary deodorant compounds therefore include, but are not limited to, aluminum bromohydrate, potassium alum, sodium aluminum chlorihydroxy lactate, aluminum sulfate, aluminum chlorohydrate, aluminum-zirconium tetrachlorohydrate, an aluminum-zirconium polychlorohydrate complexed with glycine, aluminum-zirconium trichlorohydrate, aluminum-zirconium octachlorohydrate, aluminum sesquichlorohydrate, aluminum sesquichlorohydrex PG, aluminum chlorohydrex PEG, aluminum zirconium octachlorohydrex glycine complex, aluminum zirconium pentachlorohydrex glycine complex, aluminum zirconium tetrachlorohydrex glycine complex, aluminum zirconium trichlorohydrex glycine complex, aluminum chlorohydrex PG, zirconium chlorohydrate, aluminum dichlorohydrate, aluminum dichlorohydrex PEG, aluminum dichlorohydrex PG, aluminum sesquichlorohydrex PG, aluminum chloride, aluminum zirconium pentachlorohydrate, numerous other useful antiperspirant compounds listed in the CTFA Handbook at p. 56, incorporated herein by reference, and mixtures thereof.

In addition to the astringent salts, the deodorant compound can be a bacteriostatic quaternary ammonium compound, such as, for example, cetyl trimethyl ammonium bromide, cetyl pyridinium chloride, benzethonium chloride, diisobutylbenzoxyethoxyethyl-dimethylbenzyl ammonium chloride, sodium N-lauryl sarcosine, sodium N-polymethyl sarcosine, lauroyl sarcosine, N-myristolyl glycine, potassium N-lauroyl sarcosine, and stearyl trimethyl ammonium chloride; or a bioactive compound; or a carbonate or bicarbonate salt, such as, for example, the alkali metal carbonates and bicarbonates, and the ammonium and tetraalkylammonium carbonates and bicarbonates.

In addition, other compounds can be included in the primary emulsion as the first topically active compound in an amount sufficient to perform their intended function. For example, if the composition is intended to be a sunscreen then compounds such as benzophenone-4, trihydroxycinnamic acid and salts, tannic acid, uric acid, quinine salts dihydroxy naphtholic acid; an anthranilate, diethanolamine methoxycinnamate, p-aminobenzoic acid, phenylbenzimidazole sulfonic acid, PEG-25 p-aminobenzoic acid or triethanolamine salicylate can be incorporated into the internal aqueous W₁ phase.

Further, sunscreen compounds such as dioxybenzone, ethyl 4-[bis(hydroxypropyl)] aminobenzoate, glyceryl aminobenzoate, homosalate, menthyl anthranilate, octocrylene, octyl methoxycinnamate, octyl salicylate, oxybenzone, padimate O, red petrolatum, titanium dioxide, 4-menthylbenzylidene camphor, benzophenone-1, benzophenone-2, benzophenone-7, benzophenone-12, isopropyl dibenzoyl methane, butyl methoxydibenzoylmethane, zotocrylene, or zinc oxide can be incorporated into the oil phase of the primary emulsion. Other sunscreen compounds soluble in either the aqueous or organic phase are listed in CTFA Handbook, pages 87 and 87, incorporated herein by reference.

Similarly, topically active drugs, like antifungal compounds, antibacterial compounds; anti-inflammatory compounds; topical anesthetics; skin rash, skin disease and dermatitis medications; and anti-itch and irritation reducing compounds can be included in the compositions of the present invention. For example, analgesics such as benzocaine, dyclonine hydrochloride, aloe vera and the like; anesthetics such as butamben picrate, lidocaine hydrochloride, xylocaine and the like; antibacterials and antiseptics, such as povidone-iodine, polymyxin sulfate-bacitracin, zinc-neomycin sulfate-hydrocortisone, chloramphenicol, methylbenzethonium chloride, and erythromycin and the like; antiparastitics, such as lindane; deodorants, such as chlorophyllin copper complex, aluminum chloride, aluminum chloride hexahydrate, and methylbenzethonium chloride; essentially all dermatologicals, like acne preparations, such as benzoyl peroxide, erythromycinbenzoyl peroxide, clindamycin phosphate, 5,7-dichloro-8-hydroxyquinoline, and the like; anti-inflammatory agents, such as alcometasone dipropionate, betamethasone velerate, and the like; burn relief ointments, such as o-amine-p-toluene sulfonamide monoacetate and the like; depigmenting agents, such as monobenzone; dermatitis relief agents, such as the active steroid acinonide, diflorasone diacetate, hydrocortisone, and the like; diaper rash relief agents, such as methylbenzethonium chloride and the like; emollients and moisturizers, such as mineral oil, PEG-4 dilaurate, lanolin oil, petrolatum, mineral wax and the like; fungicides, such as butocouazole nitrate, haloprogen, clotrimazole, and the like; herpes treatment drugs, such as O-[(2-hydroxyethoxy)-methyl]guanine; pruritic medications, such as alcometasone dipropionate, betamethasone valerate, isopropyl myristate MSD, and the like; psoriasis, seborrhea ad scabicide agents, such as anthralin, methoxsalen, coal tar and the like; steroids, such as 2-(acetyloxy)-9-fluoro-1′,2′,3′,4′-tetrahydro-11-hydroxypregna-1,4-dieno[16,17-b]naphthalene3,20-dione and 21-chloro-9-fluro-1′,2′,3′,4′-tetrahydro-11b-hydroxypregna-1,4-dienol[16z, 17-b]naphthalene-3,20-dione. Any other medication capable of topical administration also can be incorporated in a composition of the present invention in an amount sufficient to perform its intended function. Other topically active compounds are listed in Remington's Pharmaceutical Sciences, 17th Ed., Merck Publishing Co, Easton, Pa. (1985), pages 773-791 and pages 1054-1048 (hereinafter Remington's), incorporated herein by reference.

An above-described first topically active compound is designed to remain on the skin or hair to perform its intended function. However, in particular situations, a first topically active compound that is rinsed from the skin or hair can be incorporated into the internal aqueous W₁ phase of the primary emulsion.

For example, a W₁-O-W₂ multiple emulsion composition designed as a permanent wave composition can incorporate a reducing agent into the external aqueous phase as the second topically active compound. After applying the W₁-O-W₂ composition to the hair and allowing the composition to contact the hair for a sufficient time to reduce the hair, the external aqueous phase is rinsed from the hair leaving droplets of the primary emulsion on the hair.

The primary emulsion has incorporated therein an oxidizing agent as the first topically active compound. After the oil phase, and preferably a volatile oil phase, evaporates from the primary emulsion, the oxidizing agent is released to neutralize the hair and any reducing agent remaining on the hair. Excess oxidizing agent then can be rinsed from the hair in a second rinsing step.

Exemplary, but non-limiting, oxidizing agents used as the first topically active compound are ammonium persulfate, hydrogen peroxide, potassium bromate, potassium chromate, potassium persulfate, sodium bromate, sodium carbonate, peroxide, sodium iodate, sodium perborate, sodium persulfate, urea peroxide, and mixtures thereof. An oxidizing agent also can be the second topically active compound when the first topically active compound is a hair conditioner. In addition, the second topically active compound can be a bleaching agent (i.e., an oxidizing agent) and the first topically active compound can be a hair dye.

In preferred embodiments of the invention, the topically active compound should not be cationic in nature, particularly if anionic surfactants are used.

Water

Sufficient water is present in the aqueous phase such that the aqueous phase comprises about 1% to about 99% by weight of the W₁O. Total water present in the W₁-O-W₂ multiple emulsion composition is about 30% to about 99.9%, and typically about 40% to about 95%, by weight of the composition.

Solutes

The internal aqueous phase must also include oil-insoluble solute(s). The solutes are introduced to balance osmotic pressure. Among solutes which may be added are organic or inorganic salts such as alkali metal chlorides, sulfates, nitrates, benzoates and acetates and sugars and sugar derivatives, for example glucose and sucrose. Solute, when added to the internal aqueous phase, comprises 0.01 to 30% by wt., preferably 0.1 to 20%, most preferably 0.5 to 15%.

Optionals

It is also possible to add surfactant to the internal aqueous phase though this is added generally to the external W₂ phase. The surfactant can be any of the surfactants discussed in connection with the W₂ phase below.

The internal aqueous phase also can include optional ingredients traditionally included in topically applied compositions. These optional ingredients include, but are not limited to, dyes, fragrances, preservatives, antioxidants, detackifying agents, and similar types of compounds. The optional ingredients are included in the internal aqueous phase of the primary emulsion in an amount sufficient to perform their intended function.

Oil

The oil may be volatile (except for silicone) or nonvolatile.

A volatile oil may comprise a volatile hydrocarbon oil which evaporates during the process of drying skin or hair, and thereby releases the internal aqueous W₁ phase, which includes the first topically active compound to contact the skin or hair. This oil preferably should contain no volatile silicone since volatile silicones tend to destabilize the multiple emulsion.

In one embodiment, the oil may comprise a combination of a volatile oil (except for silicone) and a nonvolatile oil. In this embodiment, an oil can be designed to evaporate at a pre-selected temperature and provide a controlled release of the first topically active compound at the pre-selected temperature. Pre-selected temperatures are those encountered during normal hair drying, provided by a hair dryer, or provided by a curling iron.

As previously stated, the oil also can include a water insoluble topically active compound in a sufficient amount to impart a particular functional or esthetic effect (e.g., emolliency), as long as the topically active compound does not adversely affect the W₁-O-W₂ multiple emulsion composition (e.g., does not impart emulsion instability).

Although the oil can incorporate a topically active compound, the topically active compound preferably is incorporated into the internal aqueous phase.

The volatile oil preferably comprises a volatile hydrocarbon compound, such as a hydrocarbon having about 10 to about 30 carbon atoms, that has sufficient volatility to slowly volatilize from the skin or hair after application of the W₁-O-W₂ multiple emulsion composition to the skin or hair and subsequent rinsing. A preferred volatile hydrocarbon compound is an aliphatic hydrocarbon having about 12 to about 24 carbon atoms, and having a boiling point of about 100° C. to about 250° C.

Volatile hydrocarbon compounds incorporated into the primary emulsion include, for example, isododecane and isohexadecane, i.e., PERMETHYL 99A, PERMETHYL 101A and PERMETHYL 102A, available from Presperse, Inc., South Plainfield, N.J. Other exemplary volatile hydrocarbon compounds are depicted in general structural formula (I), wherein m ranges from 2 to 5.

Another exemplary volatile hydrocarbon compound is ISOPAR M (a C₁₃-C₁₄ isoparaffin available from Exxon Chemical Co., Baytown, Tex). Preferably, the volatile hydrocarbon is less than 50% unsaturated.

As previously stated, the oil also can be a nonvolatile oil. The nonvolatile oil comprises a nonvolatile silicone compound, a nonvolatile hydrocarbon, or a mixture thereof. Preferably, the nonvolatile oil comprises compounds which contain less than 50% unsaturation. The nonvolatile oil phase does not evaporate from the skin or hair. The first topically active compound therefore is released by rubbing the skin or hair to rupture the W₁/O emulsion. A nonvolatile oil has a boiling point at atmospheric pressure of greater than about 250° C.

Exemplary nonvolatile silicone compounds include a polyalkyl siloxane, a polyaryl siloxane or a polyalkylaryl siloxane. Mix of these nonvolatile silicone compounds also are useful. The nonvolatile silicones are nonfunctional siloxanes or siloxane mixtures having a viscosity of about 10 to about 600,000 cs, and typically about 350 to about 10,000 cs, at 25° C. The so-called “rigid silicones”, as described in U.S. Pat. No. 4,902,499, herein incorporated by reference, having a viscosity above 600,000 cs at 20° C., and a weight average molecular weight of at least about 500,000, also are useful in a composition of the present invention. A phenyltrimethicone also is useful as a nonvolatile silicone compound.

The preferred nonvolatile silicone compound is a nonvolatile polydimethylsiloxane compound, such as a mixture, in about a 2:1 weight ratio, of a low molecular weight polydimethylsiloxane fluid and a higher molecular weight polydimethylsiloxane gum. Preferred silicone gums include linear and branched polydimethylsiloxanes of the following general formula:

(CH₃)₃SiO—[Si(CH₃)₂O]_(n)—Si(CH₃)₃,

wherein n is a number from about 2,000 to about 15,000, and preferably from about 2,000 to about 7,000. Silicone gums useful in compositions of the present invention are available from a variety of commercial sources, including General Electric Company, Waterford, N.Y. and Dow Corning Corp., Midland, Mich.

The nonvolatile oil also can comprise a nonvolatile hydrocarbon compound, such as mineral oil. Other exemplary nonvolatile hydrocarbon compounds that can be used as the oil include, but are not limited to, a branched 1-decene oligomer, like 1-decene dimer or a polydecene.

The oil also optionally can comprise (1) an oil, such as jojoba oil, wheat germ oil or purcellin oil; or (2) a water insoluble emollient, such as, for example, an ester having at least about 10 carbon atoms, and preferably about 10 to about 32 carbon atoms.

Suitable esters include those comprising an aliphatic alcohol having about eight to about twenty carbon atoms and an aliphatic or aromatic carboxylic acid including from two to about twelve carbon atoms, or conversely, an aliphatic alcohol having two to about twelve carbon atoms with an aliphatic or aromatic carboxylic acid including about eight to about twenty carbon atoms. The ester is either straight chained or branched. Preferably, the ester has a molecular wt. of less than about 500. Suitable esters therefore include, for example, but are not limited to:

(a) aliphatic monohydric alcohol esters, including but not limited to:

myristyl propionate,

isopropyl isostearate,

isopropyl myristate,

isopropyl palmitate,

cetyl acetate,

cetyl propionate,

cetyl stearate,

isodecyl neopentanotate,

cetyl octanoate,

isocetyl stearate;

(b) aliphatic di- and tri-esters of polycarboxylic acids, including but not limited to:

diisopropyl adipate,

diisotstearyl fumarate,

dioctyl adipate, and

triisostearyl citrate;

(c) aliphatic polyhydric alcohol esters, including but not limited to:

propylene glycol dipelargonate;

(d) aliphatic esters of aromatic acids, including but not limited to:

C₁₂-C₁₅ alcohol esters of benzoic acid,

octyl salicylate,

sucrose benzoate, and

dioctyl phthalate.

Numerous other esters are listed in the CTFA Handbook at pages 24 through 26, incorporated herein by reference.

Low HLB Emulsifier

The O phase of the present invention also includes about 0.1% to about 30%, and preferably about 1% to about 15% on the weight of the oil of a low HLB emulsifier.

The low HLB emulsifier may comprise a silicon-free surfactant, or a blend of silicon-free surfactants, having an HLB value of about less than 10 (i.e., an HLB value of about 0.1 to about less than 10), an oil-soluble silicon-based surfactant, an oil-soluble polymeric surfactant, or mixtures thereof. Preferably, the silicon-free surfactant or surfactant blend has an HLB value of about 1 to about 7. To achieve the full advantage of the present invention, the silicon-free surfactant or surfactant blend has an HLB value of about 3 to about 6. The term “oil-soluble” as used herein means a compound having a solubility of at least 0.1 g per 100 ml of oil phase to form a true solution.

The HLB value of a particular surfactant can be found in McCutcheon's Emulsifiers and Detergent, North American and International Editions, MC Publishing, Glen Rock, N.J. (1993) (hereinafter McCutcheon's). Alternatively, the HLB value of a particular surfactant can be estimated by dividing the weight percent of oxyethylene in the surfactant by five (for surfactants including only ethoxy moieties). In addition, the HLB value of a surfactant blend can be estimated by the following formula:

HLB=(wt. % A)(HLB _(A))+(wt. % B)(HLB _(B)),

wherein wt. % A and wt. % B are the weight percent of surfactants A and B in the silicon-free surfactant blend, and HLB_(A) and HLB_(B) are the HLB values for surfactants A and B, respectively.

Low HLB surfactant can be a silicone-based surfactant or silicone free surfactant.

Exemplary classes of silicon-free nonionic surfactants include, but are not limited to, polyoxyethylene ethers of fatty (C₆-C₂₂) alcohols, polyoxyethylene/polyoxypropylene ethers of fatty (C₆-C₂₂) alcohols, ethoxylated alkylphenols, polyethylene glycol ethers of methyl glucose, polyethylene glycol ethers of sorbitol, and mixtures thereof.

Exemplary silicon-free nonionic surfactants are the ethoxylated alcohols having an HLB value of about 0.1 to about 10. An especially preferred ethoxylated alcohol is laureth-1, i.e., lauryl alcohol ethoxylated with an average of one mole of ethylene oxide. Other suitable ethoxylated alcohols include laureth-2, laureth-3 and laureth-4. Numerous other nonionic surfactants having an HLB of about 0.1 to about 10 are listed in McCutcheon's at pages 229-236, incorporated herein by reference. Other exemplary silicon-free nonionic surfactants having an HLB value of about 0.1 to about 10 include, but are not limited to, the ethoxylated nonylphenols, ethoxylated octylphenols, ethoxylated dodecylphenols, ethoxylated fatty (C₆-C₂₂) alcohols having four or fewer ethylene oxide moieties, oleth-2, steareth-3, steareth-2, ceteth-2, oleth-3, and mixtures thereof.

The emulsifier can also comprise a silicon-free surfactant blend having an HLB value of about 1 to about 10. The blend is a mixture of a sufficient amount of a surfactant having allow HLB value, i.e., about 0.1 to about 10, and a sufficient amount of a surfactant having a higher HLB value, i.e., about 1 to greater than about 10, such that the surfactant blend has an HLB value of about 1 to about 10. Exemplary, but non-limiting, nonionic surfactants having a high HLB value are listed in McCutcheon's at pages 236-246, incorporated herein by reference.

A preferred silicone free surfactant is PEG 30 dipolyhydroxystearate.

An exemplary oil-soluble silicon-based surfactant is a dimethicone copolyol, which is a dimethylsiloxane polymer having polyoxyethylene and/or polyoxypropylene side chains, such as DOW CORNING 3225C and 5225C FORMULATION AID, available from Dow Corning Co., Midland, Mich. The dimethicone copolyol has about 15 or fewer ethylene oxide and/or propylene oxide monomer units, in total, in the side chains. Dimethicone copolyols conventionally are used in conjunction with silicones because the silicon-containing surfactants are extremely soluble in a volatile or a nonvolatile silicone compound, are extremely insoluble in water, and have a low skin irritancy potential.

Another exemplary, but non-limiting, oil-soluble, silicon-based surfactant is an alkyl dimethicone copolyol, such as cetyl dimethicone copolyol available commercially as ABIL® EM 90 from Goldschmidt Chemical Corporation, Hopewell, Va. The alkyl dimethicone copolyols have the structure:

wherein:

p is a numeral from 7 through 17;

q is a numeral from 1 through 100;

m is a numeral from 1 through 40;

n is a numeral from 0 through 200; and

PE is (C₂H₄O)_(a)(C₃H₆O)_(b)—H having a molecular weight of about 250 to about 2000, wherein a and b are selected such that the weight ratio of C₂H₄O/C₃H₆O is from 100/0 to 20/80.

The surfactant phase also can comprise an oil-soluble polymeric surfactant. Polymeric surfactants capable of forming water-in-oil emulsions completely cover the surface of the water droplet, are firmly anchored at the oil-water interface, the external oil phase is a good solvent for the stabilizing portion of the polymeric surfactant, and the thickness of the polymer layer on the oil side of the interface is sufficient to ensure stability. These surfactants may include ethoxy, propoxy and/or similar alkylene oxide monomer units, e.g., butoxy. The oil-soluble polymeric surfactants act as surfactants and are not physically or chemically cross-linked in solution. The oil-soluble polymeric surfactants therefore are differentiated from polymeric gelling agents such as polyacrylic acid or polymethacrylic acid.

Accordingly, exemplary oil-soluble polymeric surfactants include, but are not limited to, polyoxyethylene-polyoxypropylene block copolymers, and similar polyoxyalkylene block copolymers. The oil-soluble block copolymers typically have less than about 20% by weight of ethylene oxide. Specific non-limiting oil-soluble polymeric surfactants include Poloxamer 101, Poloxamer 105, PPG-2-Buteth-3, PPG-3-Butech-5, PPG-5-Butech-7, PPG-7-Butech-10, PPG-9-Buteth-12, PPG-12-Buteth-16, PPG-15-Buteth-20, PPG-20-Buteth-30, PPG-24-Buteth-27, PPG-28-Buteth-35, and PEG-15 Butanediol. Other useful oil-soluble polymeric surfactants are polyamines, i.e., polyoxyethylene-polyoxypropylene block copolymers of ethylene diamine, having less than about 40% by weight ethylene oxide.

In accordance with an important feature of the present invention, the hydrophobic moiety of a silicon-free surfactant, silicon-containing surfactant or polymeric surfactant is sufficiently soluble in the oil phase such that a sufficient amount of the surfactant is present in the oil phase to stabilize the primary W₁/O emulsion. In one embodiment when the oil phase comprises a silicone compound, the surfactant phase comprises either a silicon-based surfactant, a silicon-free surfactant having a hydrophobic moiety preferably containing about ten to about fourteen carbon atoms, an oil-soluble polymeric surfactant, or a mixture thereof. If the hydrophobic moiety of the silicon-free surfactant is saturated and includes more than about 14 carbon atoms, the silicon-free surfactant is insoluble in the silicone phase and the primary W₁/O emulsion is unstable. If the hydrophobic moiety includes less than about 10 carbon atoms, the primary W₁/O emulsion has a tendency to coalesce i.e., the emulsion droplets fuse to form large droplets. The amount of surfactant phase necessary to provide a primary emulsion of desired W₁/O droplet diameter varies with the amount of aqueous phase in the primary emulsion and is easily determined by those skilled in the art.

One particularly preferred emulsifier is cetyl dimethicone copolyol.

The External Aqueous Phase

The external aqueous phase (W₂) of the W₁-O-W₂ multiple emulsion comprises a relatively high level of surfactant(s) that form an isotropic phase, a second topically effective compound, typically 0-40% by wt. of the external phase to perform a function identical to, similar to or different from the first topically active compound, solute, and 0.01 to 10% stabilizing natural gum polymer. The composition contains all non-amido anionic or all amphoteric surfactant, or combinations of the two. The surfactant typically will comprise 2-80% of the aqueous phase.

The anionic surfactant may be, for example, an aliphatic sulfonate, such as a primary alkane (e.g., C₈-C₂₂) sulfonate, primary alkane (e.g., C₈-C₂₂) disulfonate, C₈-C₂₂ alkene sulfonate, C₈-C₂₂ hydroxyalkane sulfonate or alkyl glyceryl ether sulfonate (AGS); or an aromatic sulfonate such as alkyl benzene sulfonate.

The anionic may also be an alkyl sulfate (e.g., C₁₂-C₁₈ alkyl sulfate) or alkyl ether sulfate (including alkyl glyceryl ether sulfates). Among the alkyl ether sulfates are those having the formula:

RO(CH₂CH₂O)_(n)SO₃M

wherein R is an alkyl or alkenyl having 8 to 18 carbons, preferably 12 to 18 carbons, n has an average value of greater than 1.0, preferably between 2 and 3; and M is a solubilizing cation such as sodium, potassium, ammonium or substituted ammonium. Ammonium and sodium lauryl ether sulfates are preferred.

The anionic may also be alkyl sulfosuccinates (including mono- and dialkyl, e.g., C₆-C₂₂ sulfosuccinates); alkyl and acyl taurates, alkyl and acyl sarcosinates, sulfoacetates, C₈-C₂₂ alkyl phosphates and phosphates, alkyl phosphate esters and alkoxyl alkyl phosphate esters, acyl lactates, C₈-C₂₂ monoalkyl succinates and maleates, sulphoacetates, and acyl isethionates.

Sulfosuccinates may be monoalkyl sulfosuccinates having the formula:

R⁴O₂CCH₂CH(SO₃M)CO₂M;

wherein R⁴ ranges from C₈-C₂₂ alkyl and M is a solubilizing cation and M is defined as above.

Also included are the alkoxylated citrate sulfosuccinates; and alkoxylated sulfosuccinates such as the following:

wherein n=1 to 20; and M is as defined above.

Sarcosinates are generally indicated by the formula RCON(CH₃)CH₂CO₂M, wherein R ranges from C₈ to C₂₀ alkyl and M is a solubilizing cation.

Taurates are generally identified by formula

R²CONR³CH₂CH₂SO₃M

wherein R² ranges from C₈-C₂₀ alkyl, R³ ranges from C₁-C₄ alkyl and M is a solubilizing cation.

Another class of anionics are carboxylates such as follows:

R—(CH₂CH₂O)_(n)CO₂M

wherein R is C₈ to C₂₀ alkyl; n is 0 to 20; and M is as defined above.

Another carboxylate which can be used is amido alkyl polypeptide carboxylates such as, for example, Monteine LCQ® by Seppic.

Another surfactant which may be used are the C₈-C₁₈ acyl isethionates. These esters are prepared by reaction between alkali metal isethionate with mixed aliphatic fatty acids having from 6 to 18 carbon atoms and an iodine value of less than 20. At least 75% of the mixed fatty acids have from 12 to 18 carbon atoms and up to 25% have from 6 to 10 carbon atoms.

Acyl isethionates, when present, will generally range from about 0.5-15% by weight of the total composition. Preferably, this component is present from about 1 to about 10%.

The acyl isethionate may be an alkoxylated isethionate such as is described in llardi et al., U.S. Pat. No. 5,393,466, hereby incorporated by reference into the subject application. This compound has the general formula:

wherein R is an alkyl group having 8 to 18 carbons, m is an integer from 1 to 4, X and Y are hydrogen or an alkyl group having 1 to 4 carbons and M⁺ is a monovalent cation such as, for example, sodium, potassium or ammonium.

Particularly preferred anionics are sodium lauryl ether sulfate and sodium dodecyl sulfate.

In general the anionic component will comprise from about 1 to 30% by weight of the composition, preferably 2 to 25%, most preferably 5 to 20% by weight of the composition.

Zwitterionic and Amphoteric Surfactants

Zwitterionic surfactants are exemplified by those which can be broadly described as derivatives of aliphatic quaternary ammonium, phosphonium, and sulfonium compounds, in which the aliphatic radicals can be straight or branched chain, and wherein one of the aliphatic substituents contains from about 8 to about 18 carbon atoms and one contains an anionic group, e.g., carboxy, sulfonate, sulfate, phosphate, or phosphonate. A general formula for these compounds is:

wherein R² contains an alkyl, alkenyl, or hydroxy alkyl radical of from about 8 to about 18 carbon atoms, from 0 to about 10 ethylene oxide moieties and from 0 to about 1 glyceryl moiety; Y is selected from the group consisting of nitrogen, phosphorus, and sulfur atoms; R³ is an alkyl or monohydroxyalkyl group containing about 1 to about 3 carbon atoms; X is 1 when Y is a sulfur atom, and 2 when Y is a nitrogen or phosphorus atom; R⁴ is an alkylene or hydroxyalkylene of from about 1 to about 4 carbon atoms and Z is a radical selected from the group consisting of carboxylate, sulfonate, sulfate, phosphonate, and phosphate groups.

Examples of such surfactants include:

4-[N,N-di(2-hydroxyethyl)-N-octadecylammonio]-butane-1-carboxylate;

5-[S-3-hydroxypropyl-S-hexadecylsulfonio]-3-hydroxypentane-1-sulfate;

3-[P,P-diethyl-P-3,6,9-trioxatetradexocylphosphonio]-2-hydroxypropane-1-phosphate;

3-[N,N-dipropyl-N-3-dodecoxy-2-hydroxypropylammonio]-propane-1-phosphonate;

3-(N,N-dimethyl-N-hexadecylammonio)propane-1-sulfonate;

3-(N,N-dimethyl-N-hexadecylammonio)-2-hydroxypropane-1-sulfonate;

4-[N,N-di(2-hydroxyethyl)-N-(2-hydroxydodecyl)ammonio]-butane-1-carboxylate;

3-[S-ethyl-S-(3-dodecoxy-2-hydroxypropyl)sulfonio]-propane-1-phosphate;

3-[P,P-dimethyl-P-dodecylphosphonio]-propane-1-phosphonate; and

5-[N,N-di(3-hydroxypropyl)-N-hexadecylammonio]-2-hydroxy-pentane-1-sulfate.

Amphoteric detergents which may be used in this invention include at least one acid group. This may be a carboxylic or a sulphonic acid group. They should generally include an alkyl or alkenyl group of 7 to 18 carbon atoms.

Suitable amphoteric detergents within the above general formula include simple betaines of formula:

where R¹ is alkyl or alkenyl of 7 to 18 carbons; R² and R³ are each independently alkyl, hydroxyalkyl or carboxyalkyl of 2 to 3 carbon atoms.

R¹ may in particular be a mixture of C₁₂ and C₁₄ alkyl groups derived from coconut so that at least half, preferably at least three quarters of the groups R¹ have 10 to 14 carbon atoms. R² and R³ are preferably methyl.

A further possibility is that the amphoteric detergent is a sulphobetaine of formula

where m is 2 or 3, or variants of these in which —(CH₂)₃SO⁻ ₃ is replaced by

In these formulae R¹, R² and R³ are as discussed previously.

The amphoteric/zwitterionic generally comprises about 1 to 30% by weight, preferably 2 to 25% of the composition, more preferably 5 to 20%. The surfactant comprises at least 50% of surfactant system.

The external aqueous phase according to the invention must also be comprised of 0.01 to 10% stabilizing natural gum polymer. It is preferred that in systems where the external surfactant W2 is comprised entirely of or contains a majority of anionic surfactant (60% or higher) that a nonionic gum polymer is used.

Particularly soluble and dispersible in anionic surfactants and anionic rich surfactant systems are the nonionic seed polysaccharides. One such stabilizer is guar gum, which is structurally composed of a straight chain of D-mannose with a D-galactose side chain on approximately every other mannose unit. The usual ratio of mannose to galactose is approximately 2:1 and molecular weights are usually on the order of 100,000 to 1,000,000. Another useful stabilizer is locust bean gum, a galactomannan consisting of a main chain of D-mannose units with single galactose side chains on approximately every fourth unit. As with guar gum, approximate molecular weights are between 100,000 and 1,000,000.

In systems where the external surfactant W2 is comprised entirely of or contains a majority (50% or higher) of amphoteric surfactant, an anionic gum polymer is preferred. These can be seaweed polysaccharides, exudate polysaccharides, or microbial polysaccharides.

A preferred anionic seaweed polysaccharide is carrageenan, or “Irish moss,” a complex mixture of sulfated polysaccharides. Carrageenan is a mixture of galactans that carry varying proportions of half-ester sulfate groups linked to one or more of the hydroxyl groups of the galactose units, which are joined by alternating α-1,3 and β-1,4 glycosidic linkages. The molecular weight usually ranges from 100,000 to 1,000,000.

A preferred anionic exudate polysaccharide is gum tragacanth, a complex mixture of acidic polysaccharides containing galacturonic acid, galactose, fucose, xylose, and arabinose. Another preferred anionic exudate polysaccharide is gum karaya, a partially acetylated high molecular weight polysaccharide which contains L-rhamnose, D-galactose, D-galacturonic acid, and D-glucuronic acid residues.

Most preferred in amphoteric surfactants or amphoteric rich surfactant systems are microbial anionic hetero polysaccharide gums, most preferably Xanthan gum. The primary structure of these microbial gums contains two glucose units, two mannose units, and one glucuronic acid unit.

Except in the operating and comparative examples, or where otherwise explicitly indicated, all numbers in this description indicating amounts or ratios of materials or conditions or reaction, physical properties of materials and/or use are to be understood as modified by the word “about”.

Where used in the specification, the term “comprising” is intended to include the presence of stated features, integers, steps, components but not to preclude the presence or addition of one or more features, integers, steps, components or groups thereof.

All percentages used, unless indicated otherwise, are intended to be percentages by weight.

The following examples are intended to further illustrate the invention and are not intended to limit the invention in any way.

EXAMPLES

Multiple Emulsion Preparation

Primary (W₁/O) Emulsions

Oil Phase: The oil and the oil soluble surfactant (low HLB emulsifier) were mixed together at room temperature using overhead stirring.

Internal aqueous phase (W₁): Sodium chloride solutions with or without topically active compounds of appropriate concentrations were prepared and the pH was adjusted to 7.0.

W₁/O preparation: the oil phase (O) was charged into the vessel. The salt/topically active compound solution (W₁) was added to the oil phase steadily through the addition funnel over the course of 10-12 minutes while mixing with the side scraper (60-80 rpm). Slow addition of aqueous phase under low shear mixing is essential to obtain a stable primary emulsion. Upon complete addition of the aqueous phase, the mixing speed of the side scraper was reduced to 40 rpm and the homogenizer was turned on. Homogenization was carried out for 3 minutes each at 8000, 9500 and 13,500 rpm at room temperature. The heat generated during the homogenization process raised the temperature of the batch to ˜35° C.

Multiple Emulsion

External aqueous phase (W₂): The stabilizing gum polymer was pre-dispersed in glycerol and this premix was added to the majority surfactant in a jacketed vessel. The minority surfactant was added at 60° C. with intense mixing. The pH of each surfactant solution was pre-adjusted to 7.0. Surfactant solutions which had a gel like consistency were centrifuged at 7000 rpm for 20 minutes to remove the entrapped air.

W₁/O/W₂ preparation: The primary emulsion (W₁/O) was charged into the smaller scale vessel followed by addition of the external aqueous phase (W₂). The mixture was hand-mixed gently for 15 seconds using a spatula. This was followed by mixing with the side-scraper for 8 minutes at 70-105 rpm (higher speed was used when mixing at lower speed was found to be inadequate). A small spatula was inserted into the vessel as a baffle to ensure good mixing around the center spindle of the side scraper. The resulting multiple emulsions were transferred into 250 ml separatory funnels to monitor phase separation over time.

Definition and Measurement of Stability

Multiple emulsion stability was measured after 45 days by collecting the amount of separated water phase (if any) and measuring the weight of collected material. This weight is then divided by the total weight of product in the separatory funnel to obtain % separation.

Materials

The following components were used in the experiments as follows:

Phase Material Supplier Trade name Function

Milli-Q Water Sodium Chloride Glycerol Potassium Hydroxide   Fisher Dow Fisher   Internal Solute Benefit Agent

Light Mineral (Paraffin) Oil Octyl Palmitate Cetyl dimethicone copolyol Fisher Goldschmidt Goldschmidt   Tegosoft OP Abil EM 90 Emollient Emollient Low HLB surf.

Cocoamidopropyl betaine Cocoamphoglycinate Sodium laureth sulfate (SLES) Sodium lauryl sulfate (SDS) Glycerol Locust Bean Gum Guar Gum Xanthan Gum Gum Tragacanth Gum Karaya Carrageenan Goldschmidt McIntyre Stepan Fluka Dow Fluka Fluka Fisher Fluka Fluka Fluka Tego Betain F 50 Mackam 1C Steol CS-330L Amphoteric High HLB surf. ″ Anionic High HLB Surfactant ″ Benefit Agent Nonionic Natural Gum # Stabilizer Nonionic Natural Gum Stabilizer Anionic Natural Gum Stabilizer Anionic Natural Gum Stabilizer Anionic Natural Gum Stabilizer Anionic Natural Gum Stabilizer

Examples 1-6

Formula # 1 2 3 4 5 6 W1 Phase Water 39.8 39.8 39.8 39.8 39.8 Sodium Chloride 0.2 0.2 0.2 0.2 0.2 Glycerol 2 2 2 2 2 Oil Phase Light Paraffin Oil 16.2 16.2 16.2 16.2 Octyl Palmitate 16.2 Cetyl Dimethicone copolyol 1.8 1.8 1.8 1.8 1.8 W2 Phase Water 23 22 21 22 22 66 Sodium laureth sulfate 15 15 15 15 25 Sodium lauryl sulfate 15 Glycerol 2 2 2 2 2 5 Locust Bean Gum 1 1 1 Guar Gum 2 Xanthan Gum 4 Total 100 100 100 100 100 100 % Phase Sep. d45 W2 Visc (cps) at 5 RPM W2 Visc (cps) at 50 RPM 40 60 60 0 24,000 7000 15 21,000 4500 N/A 26,000 8500 0 24,000 7500

Example 1, the control, has a Newtonian anionic external W2 phase (SLES) and it phase separates 40% over 45 days. Examples 2 and 3 show that by gelling the external phase with a nonionic natural gum stabilizer, phase separation is prevented by incorporating locust bean gum or retarded by incorporating guar gum. Example 4 shows that Locust bean gum also gels another anionic surfactant, sodium lauryl sulfate. Example 5 shows that octyl palmitate can be substituted for light mineral oil. In Example 6, we attempted to incorporate an anionic gum into an anionic surfactant but the W2 phase was not homogeneous. Examples 2-5 show the criticality that the gum must be nonionic when the surfactant is anionic.

Examples 7-14

Formula # 7 8 9 10 11 12 13 14 W1 Phase Water 34.8 34.8 34.8 34.8 34.8 34.8 34.8 Sodium Chloride 5.2 5.2 5.2 5.2 5.2 5.2 5.2 Glycerol 2 2 2 2 2 2 2 Oil Phase Light Paraffin Oil 16.2 16.2 16.2 16.2 16.2 16.2 Octyl Palmitate 16.2 Cetyl Dimethicone copolyol 1.8 1.8 1.8 1.8 1.8 1.8 1.8 W2 Phase Water 23 22 21 21 20 22 22 66 Cocoamidopropyl betaine 15 15 15 15 15 15 25 Cocoamphoglycinate 15  5 Glycerol 2 2 2 2 2 2 2 Xanthan Gum 1 1 1 Gum Tragacanth 2 Gum Karaya 2 Carrageenan 3 Locust Bean Gum  4 Total Total 100 100 100 100 100 100 100 100  % Phase Sep. d45 W2 Visc (cps) at 20 RPM % Phase Sep. d45 W2 Visc (cps) at 5 RPM W2 Visc (cps) at 50 RPM 50 80 80 0 7,000 2100 5 6,000 1400 10 6,000 1400 10 6500 1700 N/A 6000 1500 0 7,000 2300

Example 7, the control, has a Newtonian amphoteric external W2 phase (betaine) and it phase separates 50% over 45 days. Examples 8 through 12 show that by gelling the external phase with an anionic natural gum stabilizer, phase separation is prevented by incorporating xanthan gum or retarded by incorporating gum tragacanth, gum karaya, or carrageenan. Example 12 shows that xanthan gum also gels another amphoteric surfactant, cocoamphoglycinate. Example 13 show that octyl palmitate can be substituted for light mineral oil. In Example 14, we attempted to incorporate a nonionic gum into an amphoteric surfactant but the W2 phase was not homogeneous. Examples 8-13 thus show the criticality that the gum must be anionic when the surfactant is amphoteric.

Examples 15-22

Formula # 15 16 17 18 19 20 21 22 Water 39.6 39.6 39.6 39.6 36.4 36.4 36.4 36.4 W1 Phase Sodium Chloride 0.4 0.4 0.4 0.4 3.6 3.6 3.6 3.6 Glycerol 2 2 2 2 2 2 2 2 Oil Phase Light Paraffin Oil 16.2 16.2 16.2 16.2 16.2 16.2 16.2 16.2 Cetyl Dimethicone copolyol 1.8 1.8 1.8 1.8 1.8 1.8 1.8 1.8 Water 23 22 22 22 23 22 22 22 Cocoamidopropyl betaine 2 2 2 6 11 11 11 7.5 W2 Phase Sodium Laureth Sulfate 13 13 13 9 4 4 4 7.5 Glycerol 2 2 2 2 2 2 2 2 Xanthan Gum 1 1 1 Locust Bean Gum 1 1 1 Total 100 100 100 100 100 100 100 100 % Phase Sep. d45 50 40 0 0 40 40 0 0 W2 Visc (cps) at 5 RPM 100 200 27,000 30,000 4,000 4,500 8,000 28,000 W2 Visc (cps) at 50 RPM 100 350 8000 9000 500 650 2200 7600

Example 15, is a control with anionic as the majority surfactant. Example 16 and Example 17 show that when nonionic gum stabilizer (locust bean) is used, phase separation is prevented whereas when an anionic gum stabilizer (xanthan) is used , phase separation is still close to the control. Example 18 shows that the anionic ratio can be changed from 13:2 to 9:6 without phase separation. Conversely, Example 19 is a control with amphoteric as the majority surfactant. Example 20 and Example 21 show that when an anionic gum stabilizer (xanthan) is used, phase separation is prevented whereas when a nonionic gum stabilizer (locust bean) is used, phase separation is still close to the control. Example 22 shows that the amphoteric ratio can be changed from 11:4 to 7.5:7.5 without phase separation.

These examples demonstrate the criticality that when the majority surfactant is anionic, that a nonionic gum stabilizer must be used. Furthermore, when the surfactant mixture is half or greater amphoteric, an anionic gum stabilizer must be used. 

What is claimed is:
 1. A W₁-O-W₂ multiple emulsion comprising: (1) about 1% to 99% by wt. of the composition of a W₁/O emulsion comprising; (a) about 1% to 99% of said emulsion of an internal aqueous phase comprising (i) water; (ii) 0.01 to 30% by wt. emulsion solute; and (iii) optional surfactant; (b) about 0.5% to about 99% of the emulsion of an oil phase surrounding said internal aqueous phase wherein said oil is selected from the group consisting of volatile hydrocarbon, nonvolatile hydrocarbons, nonvolatile silicones and mixtures thereof; (c) about 0.1 to about 20% by wt. emulsion of a surfactant emulsifier selected from the group consisting of a silicon-free surfactant or surfactant blend having an HLB value of about 10 or less, an oil soluble silicon based surfactant, an oil-soluble polymeric surfactant and mixture thereof; and (d) a topically effective amount (0.01-40%) of a first topically active compound, which may be found in either the aqueous phase (a), oil phase (b) or both; and (2) about 1 to 99% by wt. of an external isotropic aqueous phase W₂ comprising: (a) 2 to 80% by wt. aqueous phase of a surfactant phase which comprises a non-amido anionic, or a mixture of anionic and amphoteric in which 60% by weight or greater is the anionic surfactant; (b) 0 to 60% by wt. of external phase of a second topically active compound; (c) optional solute; and (d) 0.01 to 10% of a nonionic natural gum stabilizer wherein the multiple emulsion droplets maintain their integrity and the multiple emulsion composition does not phase separate.
 2. An emulsion according to claim 1, comprising 2 to 90% by wt. W₁/O emulsion.
 3. An emulsion according to claim 2, comprising 5 to 80% by wt. W₁/O emulsion.
 4. An emulsion according to claim 1, wherein solute in internal aqueous phase is alkali metal chloride.
 5. An emulsion according to claim 1, wherein the solute in internal aqueous phase is either glucose or sucrose.
 6. An emulsion according to claim 1, wherein oil phase is 1 to 80% of the internal W₁O phase.
 7. An emulsion according to claim 1, wherein hydrocarbon is a saturated vegetable based oil.
 8. An emulsion according to claim 7, wherein oil is >50% saturated.
 9. An emulsion according to claim 7, wherein oil is >85% saturated.
 10. An emulsion according to claim 1, wherein the emulsifier (c) is cetyl dimethicone copolyol.
 11. An emulsion according to claim 1, where the natural gum stabilizing polymer is locust bean gum.
 12. An emulsion according to claim 1, where the natural gum stabilizing polymer is guar gum.
 13. An emulsion according to claim 1, which is stable at a temperature of about 25° C. after 2 weeks.
 14. An emulsion according to claim 13, which is stable after 30 days.
 15. A W₁-O-W₂ multiple emulsion comprising: (1) about 1% to 99% by wt. of the composition of a W₁/O emulsion comprising; (a) about 1% to 99% of said emulsion of an internal aqueous phase comprising (i) water; (ii) 0.01 to 30% by wt. emulsion solute; and (iii) optional surfactant; (b) about 0.5% to about 99% of the emulsion of an oil phase surrounding said internal aqueous phase wherein said oil is selected from the group consisting of volatile hydrocarbon, nonvolatile hydrocarbons, nonvolatile silicones and mixtures thereof; (c) about 0.1 to about 20% by wt. emulsion of a surfactant emulsifier selected from the group consisting of a silicon-free surfactant or surfactant blend having an HLB value of about 10 or less, an oil soluble silicon based surfactant, an oil-soluble polymeric surfactant and mixture thereof; and (d) a topically effective amount (0.01-40%) of a first topically active compound, which may be found in either the aqueous phase (a), oil phase (b) or both; and (2) about 1 to 99% by wt. of an external isotropic aqueous phase W₂ comprising: (a) 2 to 80% by wt. aqueous phase of a surfactant phase which comprises an amphoteric, or a mixture of anionic and amphoteric in which 50% by weight or greater is the amphoteric surfactant; (b) 0 to 60% by wt. of external phase of a second topically active compound; (c) optional solute; and (d) 0.01 to 10% of an anionic natural gum stabilizer wherein the multiple emulsion droplets maintain their integrity and the multiple emulsion composition does not phase separate.
 16. An emulsion according to claim 15, comprising 2 to 90% by wt. W₁/O emulsion.
 17. An emulsion according to claim 16, comprising 5 to 80% by wt. W₁/O emulsion.
 18. An emulsion according to claim 15, wherein solute in internal aqueous phase is alkali metal chloride.
 19. An emulsion according to claim 15, wherein the solute in internal aqueous phase is either glucose or sucrose.
 20. An emulsion according to claim 15, wherein oil phase is 1 to 80% of the internal W₁O phase.
 21. An emulsion according to claim 15, wherein hydrocarbon is a saturated vegetable based oil.
 22. An emulsion according to claim 21, wherein oil is >50% saturated.
 23. An emulsion according to claim 22, wherein oil is >85% saturated.
 24. An emulsion according to claim 15, wherein the emulsifier (c) is cetyl dimethicone copolyol.
 25. An emulsion according to claim 15, where the natural gum stabilizing polymer is xanthan gum.
 26. An emulsion according to claim 15, where the natural gum stabilizing polymer is tragacanth gum.
 27. An emulsion according to claim 15, where the natural gum stabilizing polymer is karaya gum.
 28. An emulsion according to claim 1, where the natural gum stabilizing polymer is carrageenan.
 29. An emulsion according to claim 15, which is stable at a temperature of about 25° C. after 2 weeks.
 30. A composition according to claim 29, which is stable after 30 days. 